Operator-carried power tools such as line trimmers, blower/vacuums, chain saws and the like are typically powered by two-cycle internal combustion engines or electric motors. Two-cycle engines have well recognized exhaust emission problems. Until relatively recently, it was believed that four-cycle engines were too heavy and could not be operated through the range of orientations necessary for an operator-carried power tool. The present applicant, however, recently introduced a commercially successful four-cycle engine powered line trimmer illustrated in U.S. Pat. Nos. 5,241,932 and 5,421,292 which are incorporated by reference herein.
The Everts '932 patent describes a number of alternative techniques for lubricating the overhead valves and rocker arms oriented in the valve chamber. A sealed lubricant system is described as a number of alternative mist lubrication systems. The mist lubrication systems enable the engine to be inclined very significantly from the vertical orientation. However, when the engine is run in the inverted position for extended periods of time, oil begins to leak from the engine breather.
It is an object of the present invention to increase the length of time an operator-carried, four-cycle engine can be run in the inverted position before oil begins to leak from the engine breather.
It is a further object of the present invention to provide simple and easy-to-manufacture engine components to block the flow of oil from the crankcase.
These objects and other features and advantages of the present invention will become apparent upon further review of the specification and the drawings.